Process for the direct synthesis of trialkoxysilane

a technology of trialkoxysilane and direct synthesis, which is applied in the direction of silicon organic compounds, chemistry apparatus and processes, and inefficient etc., can solve the problems of ineffectiveness of copper (ii) hydroxide as a catalyst precursor, ineffective formation of these silicates, and ineffective use of methanol reactants in direct synthesis processes. achieve good reaction rates, reduce the level of tetraalkoxysilan

Active Publication Date: 2007-03-15
MOMENTIVE PERFORMANCE MATERIALS INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0032] The process of this invention results in the production of trialkoxysilane with significantly reduced levels of tetraalkoxysilane by-product while providing, inter alia, good reaction rates at desirable values, avoiding or reducing deactivation, increasing silicon conversion and maintaining selectivity at high levels, particularly in continuous and semi-continuous operations.

Problems solved by technology

Japanese Patent Publication 55-28929 (1980) acknowledges that activation of silicon with CuCl does not always lead to desirable rate and selectivity.
Methane and dimethyl ether formation indicate an inefficient use of the methanol reactant.
Formation of these silicates represents inefficiency in the Direct Synthesis process.
There appears to be disagreement in the prior art about the effectiveness of copper (II) hydroxide as a catalyst precursor.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

examples 1-21

(5) Examples 1-21

[0120] Examples 1-21 illustrate that all copper hydroxides are not equally or acceptably effective in the Direct Synthesis of trimethoxysilane.

[0121] The sources of copper hydroxide are identified in Table 3. Direct Syntheses of trimethoxysilane were performed at 250° C. in the 8 liter reactor using the activation and reaction procedure described hereinabove. Each experiment required 3.5 kg THERMINOL® 59, 1.75 kg silicon, 13.2 g copper hydroxide, 5.0 g fluorosilicone defoamer and 8.95 g / min methanol. (Example 20 was run with 11 g / min methanol).

TABLE 3PERFORMANCE OF Cu(OH)2 FROM GRIFFIN, PHIBROTECH,SULCOSA, SALDECO, CUPROQUIM, SPIESS-URANIA ANDJOHNSON MATTHEY IN SINGLE BATCH DIRECT SYNTHESIS OFHSi(OCH3)3AVG.SiTMS,TMOS,RATE,SUPPLIER / EXAMPLECONV., %wt %wt %% Si / hSELGRIFFINExample 171.2491.133.597.7725.39Example 288.9592.354.046.2422.86Example 387.8982.1713.337.036.17Example 487.2486.1611.856.277.27Example 590.7689.877.596.3311.84PHIBROTECHExample 688.9592.494.726.35...

examples 22-31

(6) Examples 22-31

[0124] Examples 22-31 illustrate that copper hydroxides, which yield acceptable performance in a single batch experiment do not necessarily maintain this performance when multiple silicon charges are made to the reactor during semi-continuous or multibatch operation.

[0125] Each example consists of two or more batch reactions conducted in a single solvent charge. The first batch reaction (designated A in each example) was run up to about 60-90 percent silicon conversion with the material quantities and conditions disclosed in Examples 1-21 above according to the operations described in the general procedure. Thereafter, silicon and copper hydroxide were recharged to the residual reaction slurry so that initial weight of silicon for the second reaction was 1750 g. The weight ratio of copper hydroxide to silicon in the recharge was maintained at 0.00754. The third and subsequent batch reactions were performed in the same manner.

[0126] Table 4 lists the copper hydrox...

examples 33-42

(8) Examples 33-42

[0131] These examples show that phosphate content is a critical feature distinguishing copper hydroxides affording acceptable performance in the Direct Synthesis of trimethoxysilane from those, which do not. Acceptable performance, as defined hereinabove, means TMS>88 wt %, TMOS50% in single batch and multibatch operations.

[0132] Copper hydroxides used in Examples 1-31 were analyzed for copper content, water content, trace metals, sulfate, phosphate, chloride, surface area and particle size. All had surface areas>10 m2 / g and average particle size−1 region. Phosphate concentration was measured either as phosphorus by inductively coupled plasma spectroscopy or as phosphomolybdate by visible spectrophotometry. Table 7 summarizes the analytical data, which underpins the correlation of phosphate concentration of copper hydroxide with acceptable performance in the Direct Synthesis of trimethoxysilane.

[0133] The data of Examples 33 and 34 show that the GRIFFIN copper hy...

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Abstract

The Direct Synthesis of trialkoxysilane is carried out by conducting the Direct Synthesis reaction of silicon and alcohol, optionally in solvent, in the presence of a catalytically effective amount of Direct Synthesis catalyst and an effective catalyst-promoting amount of Direct Synthesis catalyst promoter, said promoter being an organic or inorganic compound possessing at least one phosphorus-oxygen bond.

Description

CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims priority to U.S. provisional application Ser. No. 60 / 716,728, filed Sep. 13, 2005, the entire contents of which are incorporated by reference herein.FIELD OF THE INVENTION [0002] This invention relates to the Direct Synthesis of trialkoxysilane by the catalyzed reaction of silicon with alcohol. In particular, the Direct Synthesis process of the present invention employs organic and inorganic phosphorus compounds such as copper phosphates, trialkyl phosphates and dialkyl phosphites to increase the reaction rate, promote selectivity to trialkoxysilane, control formation of tetraalkoxysilane and improve reaction stability in batchwise, semi-continuous and continuous operations. BACKGROUND OF THE INVENTION [0003] Trialkoxysilanes, especially trimethoxysilane, triethoxysilane and tri(isopropoxy)silane, are used in the production of silane coupling agents. One method of synthesis of trialkoxysilanes is directly from sil...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07F7/00
CPCC07F7/025C07F7/04
Inventor LEWIS, KENRICK M.MEREIGH, ABELLARD T.O'YOUNG, CHI-LINCAMERON, RUDOLPH A.
Owner MOMENTIVE PERFORMANCE MATERIALS INC
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